1,720,967 research outputs found
Salt-driven fibrinogen self-assembly into nanofibers and their biofunctionality
No full textFibrinogen self-assembly plays a critical role in tissue engineering and wound healing. While various methods generate fibrin-like networks, salt-induced fibrinogen self-assembly has gained attention due to its efficiency and solvent-free nature. However, the underlying mechanism remains unclear. This thesis investigates fibrinogen-salt interactions to develop reproducible nanofiber scaffolds for biomedical applications.
The study explores how different salts influence fibrinogen self-assembly in vitro. Initial findings show that salts in non-denaturing buffers are crucial for fiber formation. Further analysis examines the effects of divalent (Ca²⁺, Mg²⁺, Zn²⁺, Cu²⁺) and monovalent (Na⁺, K⁺, NH₄⁺) salts. Contrary to expectations, divalent ions, essential in clot formation, did not induce fibrinogen fiber formation, instead producing smooth layers. In contrast, monovalent salts in phosphate-buffered saline (PBS) triggered fibrinogen self-assembly after drying.
To understand this effect, different monovalent cation-anion combinations were tested. Results revealed a direct correlation between salt composition and fibrinogen morphology, with kosmotropic cations (e.g., Na⁺) and kosmotropic anions (e.g., H₂PO₄⁻) being most effective. These findings align with Hofmeister effects, suggesting that specific ion binding and hydration shell modulation drive fibrillogenesis.
Additionally, the study examines fibrinogen’s influence on sodium chloride crystal morphology, revealing a reciprocal interaction between proteins and salts. The final analysis assesses the biocompatibility of salt-induced fibrinogen nanofibers, showing increased platelet activation on fibrous surfaces.
In conclusion, this research elucidates the role of salts in fibrinogen self-assembly, offering insights into ion-driven protein structuring. These findings provide insights into controlled fibrinogen nanofiber fabrication, enhancing biomaterial applications in tissue engineering and wound healing
Sensor eletroquímico constituído de nanoplaquetas de grafite dispersas em quitosana para determinação de paracetamol em fármacos
Get PDFTCC (graduação) - Universidade Federal de Santa Catarina. Centro de Ciências Físicas e Matemáticas. Curso de Química.Neste trabalho descreve-se o desenvolvimento de um sensor eletroquímico baseado em monocamadas auto organizadas de ácido 3-mercaptopropiônico (MPA) e filme de nanoplaquetas de grafite dispersas em quitosana para a determinação de paracetamol em formulações farmacêuticas. As nanoplaquetas de grafite (NPQ) foram dispersas em uma solução de quitosana em ácido acético e ancoradas à superfície de eletrodos de ouro por meio de monocamadas auto-organizadas (SAM) de MPA. A caracterização do sensor proposto foi realizada por voltametria cíclica (CV), voltametria de onda quadrada (SWV), espectroscopia de impedância eletroquímica (EIS) e microscopia eletrônica de varredura com emissão de campo (SEM-FEG). A área eletroativa do sensor, determinada por CV empregando K4[Fe(CN)6] 5 mmol L-1 em KCl 0,1 mol L-1 como sonda redox, foi cerca de 2 vezes maior que do eletrodo de ouro. O efeito do tempo de contato com MPA na formação das SAMs e na adesão do filme foi avaliado por EIS e CV, selecionando-se um tempo de imersão do eletrodo em solução de MPA de 2 h. A voltametria de onda quadrada (SWV) foi selecionada como técnica eletroanalítica. As condições experimentais que resultaram em um melhor perfil voltamétrico para a aplicação analítica foram o emprego de tampão acetato (0,1 mol L-1, pH 5,0) como eletrólito de suporte e os parâmetros da técnica de SWV de 40 Hz de frequência, 80 mV de amplitude e 3 mV de incremento de potencial. A curva de calibração para o paracetamol foi obtida nas condições otimizadas e apresentou uma faixa linear de 1,5 a 19,2 mol L-1, com coeficiente de correlação (r) de 0,995 e limite de detecção de 0,9 mol L-1. O sensor apresentou um desempenho analítico aceitável em termos da repetibilidade intra-dia e entre eletrodos (2,5 % e 9,4%, respectivamente). A determinação de paracetamol em uma amostra farmacêutica utilizando o método proposto apresentou erro relativo de 1,7% e recuperação entre 97,3 e 101,4 %. Dessa forma, o eletrodo desenvolvido se mostrou adequado para a determinação de paracetamol em amostras farmacêuticas, sendo uma ferramenta útil para análises rápidas e com exatidão satisfatória
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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